Last year, a study proposed that deposits of carbon dioxide ice and other carbon-bearing molecules on Uranus's moon Ariel likely originated from chemical processes inside the moon—possibly even from a subsurface ocean.
New research has revealed that the surface of Uranus’ moon Ariel is coated with a significant amount of carbon dioxide ice, particularly on its trailing hemisphere, which always faces away from the moon’s direction of orbital motion.
Scientists now believe Miranda and Ariel, the smallest and second-smallest of Uranus’s five major moons, could be expelling vapour plumes - which on other moons in the solar system are thought to come from subsurface oceans.